Backfire into the intake

[emwhiteR/T]

My truck seems to be backfiring more frequently. The only thing I have noticed is that it happens after I was into the gas, left off and then get back into it. It lets off a noticeably loud "pop" under the hood and it loses power temporarily.

The last time it happened was when I took an exit and got off the gas to let it "coast" and then got back into the gas.

Most times it will happen when I leave my house, when my truck is not warmed up to operating temp.

I have a fastman 53mm TB, M1, AFE CAI, hypertech programmer set to regular tune, cat back exhaust, autolite 3923's with taylor 8.2mm wires.

What could be causing this? Could it be that TB is too big?

Any help would be greatly appreciated!

[BTLFED R/T]

My truck seems to be backfiring more frequently. The only thing I have noticed is that it happens after I was into the gas, left off and then get back into it. It lets off a noticeably loud "pop" under the hood and it loses power temporarily.

The last time it happened was when I took an exit and got off the gas to let it "coast" and then got back into the gas.

Most times it will happen when I leave my house, when my truck is not warmed up to operating temp.

I have a fastman 53mm TB, M1, AFE CAI, hypertech programmer set to regular tune, cat back exhaust, autolite 3923's with taylor 8.2mm wires.

What could be causing this? Could it be that TB is too big?

Any help would be greatly appreciated!


This happens with the M1 alot. Take that little L shaped hose on the MAP sensor (front of tb), turn it around (cap the port on the MAP sensor) and get an adapter that will allow you to run that hose to one of the unused ports on the M1. Most of the time it clears that up, and will give you a little better throttle response. Could also be the fuel synch is off.

If you have done this, disregard. I did it on my truck and it cleared it up.

[Typer00_0371]

This happens with the M1 alot. Take that little L shaped hose on the MAP sensor (front of tb), turn it around (cap the port on the MAP sensor) and get an adapter that will allow you to run that hose to one of the unused ports on the M1. Most of the time it clears that up, and will give you a little better throttle response. Could also be the fuel synch is off.

If you have done this, disregard. I did it on my truck and it cleared it up.

ya, i did that on my truck, both the map, and the sync.

[emwhiteR/T]

Thanks for the quick reply!

I relocated the vacuum hose and capped of the TB port. That helped when I had throttle stumbles after the M1.

How do I check/fix the fuel sync?

[BTLFED R/T]

Thanks for the quick reply!

I relocated the vacuum hose and capped of the TB port. That helped when I had throttle stumbles after the M1.

How do I check/fix the fuel sync?

That you will need to take it somewhere with a scanner, and the adjustment is made by turning the distributer. It should be around 0 to +4 IIRC. A dealership will do it for you, but check around for the cheapest price. Or if you know a mechanic with a scanner.

[emwhiteR/T]

I have a buddy that works at a Ford dealership thats around the corner from my house. Do you think a Ford house would have one? Which scanner is it?

I am sure he would know but I don't want to bug him at 10pm...

[BTLFED R/T]

I have a buddy that works at a Ford dealership thats around the corner from my house. Do you think a Ford house would have one? Which scanner is it?

I am sure he would know but I don't want to bug him at 10pm...

He'll prolly have what you need. :biggthumpup:

[emwhiteR/T]

Sweet, hopefully I can get him to take a look at it for me this weekend. Thanks again for all of the help!

After this, I need to get my headers on and MSD added! Will I have to recheck the fuel sync after the header install?

[Typer00_0371]

Sweet, hopefully I can get him to take a look at it for me this weekend. Thanks again for all of the help!

After this, I need to get my headers on and MSD added! Will I have to recheck the fuel sync after the header install?

once it's set, you should be fine.

after you set it, def make a mark on the distributor as a reference mark.

[mtlcafan79]

SCT would fix this too. It's an acceleration enrichment issue.

[hobiesun]

Mines doing it too now. I can't remember it doing it then I put new NGK plugs in it, seems to stumble a little when you rev it up from idle. All plugs double checked gap @.40. New cap and rotor and everything. I went one plug colder, I can't remember what the exact letters where but it was a 6 vpower. From what I read on this forum the closest match to the 3923's. It had some burn't out champions in it. I have to cross ref the # because I haven't a clue if they were even the right ones or not. I am pretty sure that the map hose thing has been done already, no fuel sync though. Ill have to check that out. Any reason why it would have a touch of stumble? Same reason? Thanks.

[mtlcafan79]

Mine only ever popped in the intake when it was lean or the sync was way off.

[emwhiteR/T]

I don't recall what I did to fix it but I haven't had that issue since this post...lol.

I do have headers and SCT now.

[User]

Mine use to do this Evan in the 2000. Set the sync and it fixed it. I used a Snapon OBD2 scanner at NTB and turned the dis. to 0. Never had the problem again, the scanner was reading +8 +10 before i fixed it.

[hobiesun]

Very cool I will have to check that out. I don't have an SCT but will that show the distributor Degree? Any other cheap obdII scanners? Maybe I can go to Advance Auto and zero it out with the parts douche in the parking lot!haha. No offense to Auto parts guys, just this one in particular.

[emwhiteR/T]

Mine use to do this Evan in the 2000. Set the sync and it fixed it. I used a Snapon OBD2 scanner at NTB and turned the dis. to 0. Never had the problem again, the scanner was reading +8 +10 before i fixed it.

Damn noob didn't notice how old the thread was! :nana:

It's not a problem anymore. Somebody bumped it looking for help with the same issue.

Very cool I will have to check that out. I don't have an SCT but will that show the distributor Degree? Any other cheap obdII scanners? Maybe I can go to Advance Auto and zero it out with the parts douche in the parking lot!haha. No offense to Auto parts guys, just this one in particular.

An SCT handheld will not show it. You will need an advanced scanner (doubtful AutoZone carries one beyond code readers) to be able to read the fuel sync.

[hobiesun]

Damn noob didn't notice how old the thread was! :nana:

It's not a problem anymore. Somebody bumped it looking for help with the same issue.



An SCT handheld will not show it. You will need an advanced scanner (doubtful AutoZone carries one beyond code readers) to be able to read the fuel sync.

Good to know. Thanks for the info.

[LITNGETR]

Were in Indiana do you live. I have an OTC scanner that I use.

[hobiesun]

Were in Indiana do you live. I have an OTC scanner that I use.

I live in LaPorte. But ten minutes away from Michigan City, Valparaiso, Chesterton, Westville, New Buffalo MI, about 25 minutes from Portage, South Haven. U?

[LITNGETR]

Terre Haute. About 2 1/2 or 3 hrs. from u.

[Five9Dak]

You can probably get rid of most of it with the fuel synch, but Sean is right- it needs a tune ultimately.